Crash Prediction Model and Its Prevention Method for Consecutive downgrade Section

摘要

This paper attempts to examine the relationship between crash occurrence and the geometriccharacteristics of consecutive downgrade section in China. A sample of 13 km of a consecutive downgradesection was selected in this paper. A total of 325 crashes were collected for the 2 years period. Two sectiondivided method were adopted, which produced one km fixed-length segment and the longitudinal gradeconsistent segment. Three general form of crash frequency prediction models were constructed, which arecrash frequency hourly prediction model, crash frequency weekly prediction model and crash frequencymonthly prediction model. Four kinds of prevention schemes were put forward, and three crash preventionmodels were used to re-estimate the crash frequency under the condition of four kinds of prevention schemes.A before-and-after study was carried out to analyse the prevention effect of four kinds of prevention schemesunder the condition of both with and without prevention scheme. The results indicate that the fixed-lengthsegment divided method is appropriate for complex alignment section. The economic benefit of scheme 1 and2 are not significant, but the economic benefit of scheme 3 and 4 are significant. It was interesting that costbenefitratio increased gradually with the increase of input cost, and the cost-benefit ratio began to declinewhile input cost went up to a certain extent.